Should I put more money in my ranger or just sell it?
 

I've owned the ranger for about a year now. I bought the truck originally for $500. It had 188k miles on it when I bought it. It's a 4.0 OHV model with an automatic 5 speed transmission. Here's a list of all the repairs I've done to it.
Changed various fluids (coolant, trans, oil, and power steering.)
4 New tires
New muffler and tailpipe
New brakes all around
New brake lines in the rear
New wheel hubs in the front on both sides
Replaced lower and upper intake gaskets
New upstream o2 sensors
New fuel filter and pump
That's all that I've done to it since I've owned it. It has some more issues that need to be addressed.

Its leaking oil out of the left valve cover
4x4 is not working
And the transmission is acting strange. (Shifting rough for the first minute of driving after the first minute of driving it shifts smooth again l, I've already checked the fluid level and its full the fluid doesn't smell burnt and isn't dirty.) Also after turning it off or putting it in park after a long drive it will slip for the first minute of driving again. After the first minute of driving it shifts smooth again.

So should I put a new trans in it or just get rid of it and get something else. It has 204k miles on it now.

It's possible the truck just needs some minor work to the valve body. Everything else is relatively minor. I don't think it's necessary to get rid of the truck unless you don't feel like putting money into the transmission. These trucks were plagued with transmission issues so finding a good used one isn't easy.

Yes, that pretty common on the thin steel valve covers, you can find new on ebay for $60-$100 depending on which side, and used as well

If you are selling then you will also have to buy

So if buying another used car you will be buying unknown issues because thats what all used vehicles are unknown to you

Better the devil you know than the devil you don't know, lol

If it were me I would address the transmission issue first to help you determine if you wanted to keep it or not. Nine times out of ten the problem you are having when it is cold is the internal seals in your unit are hardening up causing internal pressure losses. After it warms up the seals expand and the problem goes away. Your unit is going to require at minimum a soft parts overhaul (friction clutches, internal seals and gaskets, etc...). You could add a seal conditioner which will more than likely take the problem away or at least make it much better. However, it's a temporary fix because it will further deteriorate you seals. Way I see it you have a few options. Have your unit rebuilt, swap for a decent (low mileage) used one or sell it with the trans problem as is.

When you look at the price tag in doing the needed repairs I think you will have an easier time deciding what you want to do.